Feeder Size Calculator

Formula

The formula to calculate the feeder size is:

\[ FS = \frac{2 \cdot \rho \cdot I}{V \cdot PF} \]

Where:

\( FS \) is the feeder size (circular mils).
\( \rho \) is the resistivity of the conductor material (ohms per circular mil foot).
\( I \) is the current (amperes).
\( V \) is the voltage (volts).
\( PF \) is the power factor (dimensionless).

Example

Let's say the resistivity (\( \rho \)) is 10 ohms per circular mil foot, the current (\( I \)) is 100 amperes, the voltage (\( V \)) is 240 volts, and the power factor (\( PF \)) is 1. Using the formula:

\[ FS = \frac{2 \cdot 10 \cdot 100}{240 \cdot 1} \]

We get:

\[ FS = \frac{2000}{240} \approx 8.33 \text{ circular mils} \]

So, the feeder size (\( FS \)) is approximately 8.33 circular mils.

What is Feeder Size?

Feeder size refers to the cross-sectional area of an electrical feeder wire, which is necessary to carry a certain amount of current without overheating or dropping too much voltage. It is typically measured in circular mils, which is a unit of area used specifically for wires. Proper feeder sizing is crucial for the safety and efficiency of an electrical system.